Bolted double sickle cutterbar
BACKGROUND OF THE INVENTION 
     Double sickle or split sickle mowing devices such as shown in U.S. Pat. No. 3,577,716, issued to Horace G. McCarty, et al on May 4, 1971, have proved to be particularly advantageous on harvesting machines having a relatively wide cutting width, at least in part due to the counter reciprocating masses of the opposing sickles. A relatively recent innovation in the marketing of reciprocating cutterbars has been the utilization of easily removable threaded fasteners to connect the individual sickle sections to the support bar running transversely along the cutterbar, as shown in U.S. Pat. No. 4,198,803. Prior to the utilization of these threaded fasteners, knife sections were typically riveted to the support bar. 
     As can be seen in the aforementioned U.S. Pat. No. 3,577,716, this split sickle-type of cutterbar provides for an overlap of the individual sickles at the transverse center of the harvesting machine. In this overlap area, the overlapping knife sections move in close proximity to each other and can actually sever crop by shearing against each other, as well as against the knife guards, during their operative movement. This close proximate relationship requires that the fastener, e.g. rivet, not have a head protruding outwardly beyond the surface of the knife sections facing the opposing knife section against which the shearing relationship exists. 
     A combination of the teachings of the split sickle device taught in the aforementioned U.S. Pat. No. 3,577,716 and the teachings of the aforementioned U.S. Pat. No. 4,198,803, in which the rivets had been replaced by threaded fasteners, has resulted in double sickle cutterbars having threaded fasteners attaching the knife sections to the respective support bars along the entire width of the cutterbar except in the overlap area where conventional riveting has been utilized because an effective threaded fastener system has not been developed. Accordingly, it would be advantageous to provide a threaded fastener that could be used in conjunction with double sickle cutterbars in the overlap area to gain the advantages associated with the easy removal of knife sections attached to the corresponding support bar by threaded fasteners along the entire length of the cutterbar, thereby providing an improved double sickle cutterbar. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to overcome the aforementioned disadvantages of the prior art by providing a double sickle cutterbar utilizing threaded fasteners along the entire length of the cutterbar, including the overlap area. 
     It is another object of this invention to provide a special threaded fastener that can be utilized in the overlap area of a double sickle cutterbar. 
     It is a feature of this invention that the head of the fastener utilized in the overlap area of a split sickle cutterbar can be recessed within the body of the knife section. 
     It is an advantage of this invention that the head portion of the threaded fastener utilized in the overlap area of a split sickle cutterbar does not disrupt the shearing relationship between opposing knife sections in the overlap area. 
     It is another feature of this invention that the threaded fastener is provided with a non-circular intermediate portion engageable with an opening of corresponding shape in the support bar to restrict the rotational movement of the threaded fastener during installation and removal. 
     It is another advantage of this invention that the threaded fastener utilized in the overlap area of a split sickle cutterbar can be manipulated to provide a clamping load on the knife section engaged thereby through the utilization of a single tool. 
     It is still another feature of this invention that the head portion of the threaded fastener is provided with a chamfered surface engageable with a corresponding chamfered surface surrounding the hole in the knife section through which the fastener is inserted. 
     It is still another advantage of this invention that the chamfered surface on the head portion of threaded fastener can be utilized to secure a clamping load on the knife section while permitting the head portion to the countersunk into the body of the knife section. 
     It is yet another feature of this invention that the nut engageable with the threaded portion of the threaded fastener is provided with a chamfered surface engageable with a circular chamfered surface surrounding the non-circular opening through the support bar. 
     It is yet another advantage of this invention that the interengagement of the chamfered surfaces of the nut and support bar structure provides adequate clearance between the sickles and the guards in the overlap area and resists a tendency for the hardware to loosen. 
     It is a further feature of this invention that the size of the hole through the knife section permits the non-circular intermediate portion of the fastener to pass therethrough for engagement with the opening through the support bar aligned therewith. 
     It is yet another advantage of this invention that the knife sections in the overlap area of the double sickle cutterbar can be quickly and easily installed and removed with a single tool. 
     It is still another object of this invention to provide an entirely bolted double sickle cutterbar which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     These and other objects, features and advantages are accomplished according to the instant invention by providing a reciprocating cutterbar of the type utilizing a pair of counter-reciprocating sickles driven at the opposing outboard ends and overlapping at the inboard ends thereof wherein the knife sections are detachably affixed to the respective support bars of these sickles by special threaded fasteners to permit the overlapped knife sections to maintain a close shearing relationship. These special threaded fasteners include a head portion adapted to be countersunk into the body of the knife section below the surface thereof, a threaded portion adapted to be threadably engaged with a nut to effect a clamping load between the knife section and support bar, and an intermediate portion having a non-circular cross-sectional configuration engageable with a corresponding non-circular opening formed in the support bar to restrict rotation thereof when the fastener is engaged therewith. The head portion of the fastener includes a chamfered surface engageable with a corresponding chamfered surface surrounding the hole through the knife section to permit the fastener to firmly engage the knife section while being countersunk therein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a top plan view of a crop harvesting header incorporating the principles of the instant invention; 
     FIG. 2 is a partial cross-sectional view of the overlap area at the transverse center of harvesting header corresponding to lines 2--2 of FIG. 1, to provide an elevational view of the overlap area of the cutterbar; 
     FIG. 3 is an enlarged partial cross-sectional view of the overlap area showing one of the threaded fasteners utilized to attach the inner knife sections to the support bars, as seen along lines of 3--3 of FIG. 2, providing an elevational view of the threaded fastener in position for clamping the inner knife section to the support bar; 
     FIG. 4 is a detailed elevational view of the threaded fastener seen in FIG. 3; and 
     FIG. 5 is a cross-sectional view taking along lines of 5--5 of FIG. 4 to show the cross-sectional configuration of the non-circular intermediate portion of the threaded fastener. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and, particularly, to FIG. 1, a top plan view of a crop harvesting header, commonly attached to the frame of a crop harvesting machine such as a windrower or a mower-conditioner, incorporating the principles of the instant invention, can be seen. Any left and right references are used as a matter of convenience and are determined by standing behind the crop harvesting header and facing the forward end, the direction of travel, looking across the header with the cutterbar positioned at the forward edge thereof for initial engagement of standing crop material. 
     The crop harvesting header 10 is used to sever crop material from the field and effect a rearward conveyance of the severed crop material into further harvesting apparatus (not shown) carried by the machine to which the header 10 is mounted. Accordingly, the header 10 would incorporate a cutterbar 20 disposed along the forward edge thereof to engage standing crop material to effect a severing thereof from the ground. The severed crop material would then be engaged by a conventional auger 15 to consolidate the severed crop material and feed it rearwardly to additional conventional harvesting apparatus (not shown), such as a conventional conditioning mechanism. Such crop harvesting headers 10 typically are provided with a reel (not shown) to assist in the conveying of severed crop material from the cutterbar 20 to the auger 15. As can be seen in FIG. 1, the conventional reel has been deleted from the drawing to permit a better viewing of the cutterbar 20. 
     Referring now to FIGS. 1 and 2, the cutterbar 20 is provided with a left sickle 21 disposed from the left side sheet 12 toward the transverse center of the header 10 and a right sickle 25 disposed in registered alignment with the left sickle 21 and extending from the right side sheet 13 toward the transverse center of the header 10. Each sickle 21, 25 is driven by a drive mechanism 17 supported adjacent the corresponding side sheet 12, 13 and drivingly connected to the respective outboard ends 22, 26 of the left and right sickles 21, 25, respectively. The drive mechanism 17 is conventional in structure and is driven by respective drive shafts 18 operatively connected to a conventional source of rotational power (not shown). Each drive mechanism 17 converts the rotational power delivered by the drive shafts 18 into reciprocating motion for transversely moving each respective sickle 21, 25 in an opposing fashion as is known in the art. 
     One skilled in the art will readily see that the left and right sickles 21, 25, respectively, are composed of a plurality of knife sections 30 attached to an elongated, transversely extending support bar 35. Each knife section 30 has a conventional diagonally extending cutting edge forming a somewhat triangular shape to the knife section 30, and is positioned in registration with a plurality of knife guards 39 to create a shearing action therebetween to affect a severing of standing crop material from the ground. As is conventional, the guards 39 are detachably fixed to the frame 11 of the header 10 and project forwardly therefrom to support the sickles 21, 25 for transverse, reciprocal sliding movement relative thereto as induced by the drive mechanism 17. Conventional holddowns 28 engage the upper surface of the sickles 21, 25 to keep the knife sections 30 in proper shearing relationship with the guards 39. 
     The overlap area 29 can be defined as being located proximate to the transverse center of the header 10 and is provided by reason of the opposing reciprocal movement of the respective sickles 21, 25 and the need to maintain a constant shearing action along the entire transverse length of the cutterbar 20 during operation of the cutterbar. The inboard end 23 of the left sickle 21 has attached thereto three inner knife sections 32 fastened to the support bar 35 in such a manner that no portion of the fastener 40 projects above the upper surface of the inner knife sections 32. Similarly, the right sickle 25 has two inner knife sections 34 affixed to a support bar extension 37 at the inboard end 27 by fasteners 40 that have no portion thereof extending below the surface of the inner knife sections 34 facing the lower inner knife sections 32. 
     All other knife sections 30 on both the left and right sickles 21, 25 are affixed to the support bars 35 by threaded fasteners 31 equipped with hexagonal nuts in a conventional manner. The knife sections 32 are mounted on top of the support bar 35 and affixed thereto with a special threaded fastener 40 extending therethrough. The inner knife sections 34 are similarly attached below the support bar extension 37 by the special threaded fastener 40 described in greater detail below. The inner knife sections 32, 34 are operable within the overlap area 29. 
     The support bar extension 37 extends beyond the inboard end 27 of the right sickle 25 and contains a bent portion 38 that slides over the upper surface of the inner knife sections 32 to maintain a vertically spaced relationship between the left and right sickles 21, 25 during operation thereof. It can be seen that the inner knife sections 32 are maintained in a shearing relationship with the inner knife sections 34 during operation of the cutterbar 20 to effect a severing of crop material along the transverse center of the header 10. The endmost inner knife section 32 can be inverted as is known in the art to provide a more precise shearing relationship at the inboard ends 23, 27 of the respective sickles 21, 25. 
     Referring now to FIGS. 2-5, it can be seen that the special threaded fastener 40 includes a head portion 42 adapted to the countersunk into the body of the inner knife sections 32, 34, and defining one end of the fastener 40, while the opposing end of the fastener 40 is formed as a threaded portion 44 which is adapted to threadably receive a special hexagonal nut 50. The fastener 40 also includes an intermediate portion 45 positioned between the head portion 42 and the threaded portion 44. The intermediate portion 45 has a non-circular cross-sectional configuration, while both the head portion 42 and the threaded portion 44 are circular in cross-section. 
     The intermediate portion 45 is engageable with an opening 46 formed in the support bar 35 in a shape corresponding to the non-circular cross-sectional configuration of the intermediate portion 45. As seen in FIG. 5, the intermediate portion 45 is preferably square, although the shape could be any non-circular configuration so that insertion of the intermediate portion 45 into the opening 46 prevents the fastener 40 from rotating relative to the support bar 35. With respect to the inner knife section 34, the support bar extension 37 is constructed similarly to the inner end 23 of the left sickle 21 with a corresponding non-circular opening 46 extending therethrough for engagement with the intermediate portion 45 of the corresponding fastener 40. 
     The head portion 42 is provided with a chamfered surface 43 extending around the circumference thereof and being engageable with a corresponding chamfered surface 49 surrounding the hole 48 formed through the inner knife sections 32, 34. The purpose of the chamfered surface 49 extending around the head portion 42 is to allow a proper seating of head portion 42 against the relatively thin inner knife sections 32, 34, while permitting the head portion 42 to be recessed into the body of the inner knife sections 32, 34, as depicted in FIG. 3. Depending on the thickness of the inner knife section 32, 34, the head portion 42 will have the flat top surface 42a thereof positioned either flush with the surface of the knife section 32, 34 or recessed below as shown in FIG. 3. 
     To provide a wedged engagement between the fastener 40 and the support bar 35, or support bar extension 37, the opening 46 on the side of the support bar 35 or extension 37 away from the corresponding inner knife section 32, 34 is provided with a circular chamfered surface 47 surrounding the non-circular opening 46 to be engageable with a corresponding chamfered surface 52 on the nut 50. As a result, the tightening of the nut 50 on the threaded portion 44 of the fastener 40 can effect a substantial clamping load on the inner knife sections 32, 34 in the corresponding support bar 35 or support bar extension 37. Furthermore, the interengagement of the nut 50 with the chamfered surface 47 reduces the overall height of the fastener assembly 40, 50 by a partial countersinking of the nut 50 into the support member 35, 37 and also resists a tendency for the nut 50 to loosen which would create problems in the narrow confines of the overlap area 29. 
     In operation, an inner knife section 32, 34 is detachably connected to the corresponding support bar 35 or support bar extension 37 by passing the fastener 40 through a hole 48 in the inner knife section 32, 34 and an aligned opening 46 in the support bar 35 or support bar extension 37 until the intermediate portion 45 is engaged in the corresponding non-circular opening 46, thereby restricting the rotational movement of the fastener 40. A threading of the nut 50 with the chamfered surface 52 thereof adjacent the support bar 35 or support bar extension 37 will draw the head portion 32 firmly into the corresponding inner knife section 32, 34 with the chamfered surface 43 thereof engaged with the corresponding chamfered surface 49 of the hole 48. 
     A further tightening of the nut 50 on the threaded portion 44 of the fastener 40 will wedge the chamfered surface 52 of the nut 50 into the circular chamfered depression 47 formed around the non-circular opening 46 to effect a substantial clamping load fixing the respective inner knife section 32, 34 on the support bar 35 or support bar extension 37 and provide the necessary clearance between the guards 39 and the sickles 21, 25, particularly for the left sickle 21. With the head portion 42 countersunk into the corresponding inner knife section 32, 34, no portion of the fastener 40 is exposed above the surface facing the opposing inner knife section 32, 34 to interfere with the registering relationship between the inner knife sections 32 and the inner knife sections 34. Since the intermediate portion 45 prevents the fastener 40 from rotating when engaged with the support bar 35 or extension 37, the fastener can be installed with a single tool manipulating rotation of the nut 50. 
     Removal of the fastener 40 to affect a detaching of the inner knife sections 32, 34 from the corresponding support bar 35 or extension 37 can be accomplished in the opposite manner to the installation noted above. Since the fastener 40 is restricted from rotation due to the engagement of the non-circular intermediate portion 45 and the corresponding opening 46, the fastener 40 can be removed with the use of a single tool manipulating rotation of the nut 40 on the threaded portion 44 away from the support bar 35 or extension 37. As a result, a split sickle cutterbar is provided with all of the knife sections 30, 32, 34 being detachably fixed to the support bars 35 or extension 37 with threaded fasteners 31, 40. 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.